Agree this is a decent looking website, appears you worked hard for your friend. Depends what their intentions are as to whether several points apply, including if they are interested in working with search engines, along with all website visitors. A few issues which come to mind:

See they have the .co.uk version of the cottage name registered, are they intending to use this? The problem is that the site is partly indexed under the current subdomain, so if they do switch to the domain, important to put in place page by page 301 redirects from the existing subdomain to the new domain. Otherwise the duplication will cause unwanted issues.

There are a few cross browser errors to attend to, the tariff table a good example although there are others. Best to run the site up in a few different browsers and identify CSS glitches that need attention. You can't expect perfection but a few aspects are not presently good. A particular function you might look at is the navigation, not least the drop down menus.

Any user without javascript enabled can't use them, which includes users with accessibility issues and a percentage of other users who surf that way, plus a few devices. There also appear to be related issues for search engines, take a look at the Google cache of the home page:

You will see that a number of the navigation links are just text, so they may also be having problems with the navigation. They are finding/indexing pages here and there, coping to an extent but not happy, which isn't what you would want. Apart from pure discovery of pages, allowing search engines to easily understand the structure of a site is very useful.

Bearing in mind the massive code bloat employed and the other issues, possibly just as well to rip the existing navigation out and replace this with a CSS/HTML version. Not as much of a task as this might sound, can be made to look the same and far more usable/compliant. There are a few other coding points as well, which will effect how well the site works with the ever growing number of alternative devices. Appreciate your intention wasn't to build a mobile site but if you are not going to do that, nowadays worth creating something which will function to an extent on smaller screens and emerging operating systems with larger screens.

I may have gone down a more complicated road than you needed. If all they want is a site which is useful to list by URL in ads, or be found for the cottage name, plus be usable for a majority of visitors, then you are on your way. Whatever the case, they should be grateful for your hard work and pleasant rendering, just might be that to achieve what they need there's a bit to do. That's fun to learn anyway, so no harm done.

A couple of small details: the text on the Dining Out pages is a different size to the rest... and the thumbnails in the Local History Gallery, apart from being rather small, haphazardly-placed and with no explanatory captions, aren't linked to higher-res pics.

I've had great success with a similar site to promote a flat that I was letting long-term. Since 2003, it hasn't been empty and all my tenants have come to me after seeing the site click here - it's not cutting-edge and will need updating when my present tenant leaves (not in the near future, then...), but it's a whole lot better than a 2x2 Letting Agent's snap in the local paper!

...I said that all my tenants had come to me via the site. Well, I advertise in the local press when the flat becomes empty, and uniquely among private ads, I include the web site address. This has been a great help, as I don't have to describe the flat and its surroundings to prospective tenants and they know what to expect before they even call.

But you're looking for a different market, the person who is looking for a one- or two-week holiday. They'll be typing 'Lancashire accomodation' into their search engine... and, as I have just found out, they won't come up with Yarrow Cottage.

Ansolan and fourm member have posted good advice... also, Serif have some good SEO techiques in their manuals and online (try the Forums, which are very friendly and helpful)